Industrial
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User Manual
CAN /Ethernet - Converter
Document code: MN67644_ENG Revision 1.200 Page 35 of 41
Read Frames
For reading Data it is necessary to have a map in the RAM memory that contains the Data that passing in the bus. This map is implemented
in the “Compositor SW67644” but it has some standard addresses given by the software. It is possible to see this map in Fig. 6.
The Bytes that composed the request are these:
Byte Number
Description
1
Read Identifier (0x01)
2
Starting Address Hi
3
Starting Address Lo
4
Number of Byte to read Hi
5
Number of Byte to read Lo
The Bytes that composed the respons are these:
Byte Number
Description
1
Error
2÷n+1
Data
n=Number of Byte
The Error Byte (Byte 1) can have three values:
•
0x00: No error;
•
0x01: Starting Address doesn’t exist;
•
0x02: Too many Data to read.
Example:
1-
We want to read the data of the first COB-ID defined in Fig. 6.. So the string of hexadecimal numbers is:
REQ:[01][00][00][00][06]
RES:[00][01][02][03][04][05][06]
2-
We want to read the data of the second COB-ID defined in Fig. 6.. So the string of hexadecimal numbers is:
REQ:[01][00][01][00][08]
RES:[00][11][22][33][44][55][66][77][88]
3-
We want to read the data of the first and second COB-ID defined in Fig. 6. together. So the string of hexadecimal numbers is:
REQ:[01][00][00][00][0E]
RES:[00][01][02][03][04][05][06][11][22][33][44][55][66][77][88]